Suppose aaa, bbb, ccc and ddd are all non-positive integers such that the following is an algebraic identity in xxx: (x−a)2(x+a)2=x4+bx3+cx2+dx+256.(x-a)^2(x+a)^2=x^4+bx^3+cx^2+dx+256.(x−a)2(x+a)2=x4+bx3+cx2+dx+256. What is the value of −a−b−c−d-a-b-c-d−a−b−c−d?